Non-woven, lofty, three-dimensional, fibrous abrasive products have been employed to remove corrosion, excess material, surface defects, burrs and impart desirable surface finishes on various articles of aluminum, brass, copper, steel, wood and the like. Non-woven, lofty, three-dimensional, fibrous abrasive products made according to teaching of the patents described below have been in wide use for quite some time.
Various abrasive articles may be used to abrade the existing surface of the materials described above to remove existing imperfections and finalize the surfaces. Typically, coated abrasive paper, cloth or vulcanized fiber disk, (typically mounted on a powered right-angled tool) are all suitable for the foregoing initial abrasive application. Available abrasive disks, while being sufficiently aggressive and capable of accomplishing the needed rough preparation of the surface typically leave visible grinding marks on the surface which often need to be removed. Consequently, additional surface preparation is often needed to remove the grinding marks to obtain the desired finished surface. This additional corrective surface preparation includes a finishing step of using successively finer grades of coated abrasive materials or using a non-woven abrasive to sufficiently decrease surface roughness and remove the grinding marks or other small imperfections.
Non-woven abrasive surface conditioning articles have been used in a wide variety of abrasive applications and are known to leave acceptable surface finishes, and non-woven abrasive surface conditioning articles generally have long useful lives.
Non-woven and coated abrasive articles have been described in the patent literature.
U.S. Pat. No. 2,958,593 (Hoover et al.) describes low density open non-woven fibers abrasive articles having a high void volume (e.g. low density). The non-woven webs of the '593 patent are comprised of short fibers bonded together at their points of mutual contact to form a three dimensional integrated structure. Fibers may be bonded to one another with a resin/abrasive mixture, forming globules at the points of mutual contact while the interstices between the fibers remain substantially unfilled by resin or abrasive. The void volume of the disclosed structures typically exceed 90%.
U.S. Pat. No. 3,688,453 (Legacy et al.) describes abrasive articles such as belts suitable for offhand and automated article finishing. The belts comprise a lofty non-woven web that is attached to a woven backing by needle tacking. The web is impregnated with resin and abrasive. According to Example 1, the webs are coated with a resin/abrasive slurry which is then dried to provide the finished article. The resin/abrasive is applied to achieve a dry coating weight 169 grains per 4 inch by 6 inch pad (708 g/m sup 2) and then is coated with a second abrasive/adhesive slurry at 78 grains per 4 inch by 6 inch pad (327 g/m sup 2).
U.S. Pat. No. 4,331,453 (Dau et al.) describes and abrasive articles comprising a lofty, non-woven, three dimensional abrasive web adhesively bonded to stretch-resistant woven fabric with a polyurethane binder. The resin coating weights for the articles of the '453 patent, as stated in Example 1, are about 70 grains of an adhesive composition per 4 inch by 6 inch pad (293 g/m sup 2) followed by final abrasive-adhesive slurry at a dry coating weight of 225 grains per grains per 4 inch by 6 inch pad (942 g/m sup 2).
U.S. Pat. No. 5,178,646 (Barber, Jr. et al.) describes coatable thermally curable binder precursor solutions modified with a reactive diluent and an abrasive articles incorporating such binder precursor solutions. The coated abrasive articles of the '646 patent include a flexible backing such as a paper sheet or a cloth backing.
U.S. Pat. No. 5,306,319 (Krishnan et al.) describes surface treating articles utilizing an organic matrix such as non-woven web that is substantially engulfed by a tough, adherent elastomeric resinous binder system. The articles of the '319 patent principally comprise surface treating wheels.
European Patent Application 0716903 A1 describes a coated abrasive product comprised of base resin coat, abrasive mineral grains and a size resin coat all applied on flexible backing material consisting of a non-woven fiber mat. The non-woven fiber mat is formed into a flat, wear and tear resistant backing by means of a binder or by the superficial dissolving or fusing of fibers. An abrasive layer comprising abrasive grain may be coated onto one or both sides of the non-woven fiber mat.
In general, the prior art describes non-woven abrasive articles where the working surface of the non-woven abrasive article is a relatively flat, two-dimensional surface. Such non-woven abrasive articles are difficult to use on curved surfaces, especially concavely curved surfaces or surfaces with interior curves (i.e., curves less than 180 degrees), because the non-woven abrasive article must be deformed while in use through the application of force in order to conform to such curved working surfaces. The use of prior art non-woven abrasive articles on such curved surfaces tends to require a higher level of skill and attention to avoid gouging the surface or removing excess material from the surface. Even with a skilled operator, the use of flat non-woven abrasive articles tends to result in a non-uniform surface finish. In addition, the deformation of the non-woven abrasive through the application of force in use tends to weaken the non-woven abrasive, thereby reducing its useful life.
The prior art does not teach or disclose the use of a non-woven abrasive article which is preformed into a three-dimensional shape prior to its use. Such three-dimensional forming reduces or eliminates the need to deform the non-woven abrasive article through the application of force while the article is being used, thereby resulting in improved uniformity of abrading effect, lowering the level of skill required for use on curved surfaces, and prolonging the useful life of the non-woven abrasive article.